Thermostatically controlled timing relay circuit



Nov. 10, 1942. L. E. WEYENBERG 2,301,598

THERMOSTATICALLY CONTROLLED TIMING RELAY CIRCUIT Filed Aug. 2, 1940 35 fI i u r 25 6 my 20 INVENTOR 4/0/VE4 E. WEYENEEEG Patented Nov. 10, 1942THERMOSTATICALLY CONTROLLED TIMING RELAY CIRCUIT Lionel E. Weyenberg,Milwaukee, Wis., assignor to X-Ray 'Shoe Fitter, Inc., Milwaukee, Wis.,a corporation of Wisconsin Application August 2, 1940, Serial No.349,690

7 Claims.

This invention relates to improvements in thermostatically controlledtiming relay circuits.

It is the primary object of the invention to provide a control includinga time switch having a predetermined cycle of operation for regulatingthe interval that a current consuming device is energized, said timeswitch having connections such that the current consuming device isenergized immediately upon the initiation of time switch operation andremains functioning for substantially the entire period of time switchoperation instead of merely the latter half of such period.

As specifically directed to the present structure, it is the primaryobject to provide a thermostatic time switch, the movement of whichdepends upon the heating and cooling of the controlling thermostat andthe connections employed being such that the X-ray tube is energizedsubstantially immediately with the commencement of the heating of thethermostat and continues in operation throughout the heating period andthe cooling period of the thermostat.

The invention has particular application to X- ray equipment for thefitting of shoes which must frequently be handled by inexperiencedoperators and it is the primary object of the invention to avoid injuryboth to the apparatus and to the operator or to the person whose shoe isbeing Other objects will be apparent from the following disclosure ofthe invention.

The drawing shows diagrammatically the component relay devices andswitches and the circuit in which they are connected.

The X-ray tube I has its filament 2 energized by a portion of thesecondary winding 3 which supplies the voltage for the tube. Thesecondary winding 3 is part of a transformer having a core 4 and aprimary winding 5. The voltage across the primary is adjustablycontrolled by a rheostat 6. Thus far the circuit is entirelyconventional. The present invention concerns the manner in which thecurrent to the transformer is regulated.

The main supply line includes conductors l and 8, one of which iscontrolled by a switch 9 biased to be normally open. The closing ofswitch 9 initiates a series of automatic operations as will hereinafterbe described.

In the first place, the closing of switch 9 energizes the transformerprimary 5 through resistance I!) which is connected between the lineconductor 1 and th conductor 8 which lead to the primary.

In the second place, the closing of the switch at 9 almost immediatelyshunts the resistance l0 out of circuit through the operation of therelay. This relay includes a solenoid coil ll, an armature l2, a. switchcontact l3 normally biased to open position and stationary contacts I4and I5. Contact i5 is connected with conductor 8 leading to thetransformer primary and contact [4 is connected with the lineconductor 1. Consequently, the closing of the switch across contacts I4and I5 shunts the resistance I0 out of the circuit to the transformer.The operation of the relay takes place almost instantly because the coilH is connected by conductors l6 and I1 and I8 to the line conductor 8controlled by switch 9 and is connected by conductor [9 and resistance20 to the other line conductor 7. Thus the closing of switch 9 energizescoil II to operate the relay.

It is desirable in a machine of this kind, and in many other devices,that the current consuming element should begin to function immediatelywithout waiting for the thermostatic switch hereinafter described tomove through its full heating range before the tube is set in operation.

The closing of switch 9 further initiates the operation of athermostatic relay C. Conductor l8, supplied with current by the closingof switch 9, is connected by conductor 2| with resistance element 22which serves as a heater for the bimetallic thermostatic contact 23. Theother side of the resistance element 22 is connected by conductor 24through resistances 25 and 26 with the other line conductor 1 so thatthe closing of the switch heats the resistance 22.

After a predetermined period depending on the spacing between contacts21 and 28 of the thermostatic relay C, the bimetallic contact element 23of the relay C engages contact 28. This provides a shunt circuit throughthe bar 23 from conductor I8 and contact 28 directly to conductor 24,thus eliminating the resistance 22. The increased flow of currentthrough conductor 24 upon the elimination of resistance 22 is sufiicientto energize coil 29 of relay B, thereby attracting the armature 30 ofrelay B and engaging the switch 3| thereof with the contacts 32 and 33.Contact 33 is connected with conductor I! and contact 32 with conductor2t. Thus, the closing of this relay provides a shunt across theresistance element 22 of the heater in relay C, thus permittingbimetallic bar 23 to cool and to return to its original position inengagement with contact 21. At the same time, the shunt circuit providedby contact 3| of relay B continues to hold such relay closed against thebias which tends to open it.

The reengagement of the bimetallic bar 23 with contact 21 establishes anelectrical circuit from conductor 19 through the bar to conductor 24 andthence through contact 32, relay switch SI and contact 33 to conductorl6. This short circuits the winding ll of relay A, thereby permittingthe bias of switch 13 and relay A to open the relay. It will be recalledthat it was the function of relay A to shunt out the resistance i3 fromthe transformer circuit. Consequently, the opening of relay Areestablishes the circuit through resistance to the primary of thetransformer and thus virtually extinguishes the X- ray. The X-ray will,however, continue very dimly in operation so long as the operatorcontinues to hold the button 9 depressed. Release of the button 9 cutsthe current to relay B, thus allowing that relay to open and reestablishthe entire circuit in its original condition in readiness for a furthersequence of operation, as above described.

It will be apparent that with every operation of the push button switch9 by the operator, the X-ray tube will be permitted only a limitedperiod of operation at full intensity. This protects the user or patientas well as the operator and the equipment. The time interval can readilybe controlled by adjusting the contact 28 of the thermostatic relay C.

It is desirable that the resistance 10 should be cut into the circuit tothe transformer before the circuit is wholly broken. This protects theapparatus from current surges such as might follow an abruptinterruption of the circuit. However, it is broadly immaterial to theuse of a thermostatic timing relay whether the circuit be completelyinterrupted or whether it be modified by cutting in a resistance in sucha way as to make the X-ray tube inoperative on completion of the cycleabove described.

The broken line marked with reference character 35 surrounding theseveral relays A, B and C, the resistances I6, 29, and 2G and the wiringconnecting these parts indicates that these parts may, if desired, beassembled on a common panel as a unitary organization requiring only theconnection of conductors T, 8 and I8 to render it operative in the X-raycircuit.

One advantage of the specific circuit disclosed lies in the fact thatthe thermostatic bar has cooled and returned to the starting pointduring the cycle. Accordingly, a new cycle can be commenced at once, ifdesired.

I claim:

1. In combination, an electrical supply circuit, a translating device tobe connected thereto, an impedance, an electroresponsive switch, aswitch operable at will to connect said translating device to saidsupply circuit through said impedance and to effect operation of saidelectroresponsive switch to exclude said impedance from circuit forrendering said translating device active, and a thermally responsiveswitch and a second electroresponsive switch coacting to effectreinclusion of said impedance by said first mentioned electroresponsiveswitch thereby to limit duration of the active period of saidtranslating device and to maintain said device inactive pending anotheroperation of said switch operable at will.

2. In combination, an electrical supply circuit, a translating device tobe connected thereto, an impedance, an electroresponsive switch, aswitch operable at will to connect said translating device to saidsupply circuit through said impedance and to effect operation of saidelectroresponsive switch to exclude said impedance from circuit forrendering said translating device active, and a thermally responsiveswitch and a second electroresponsive switch coacting to effectreinclusion of said impedance by said first mentioned electroresponsiveswitch thereby to limit duration of the active period of saidtranslating device and to maintain said device inactive pending anotheroperation of said switch operable at will, said thermal device beinginitially subjected to a thermal influence of current of a circuitindependent of the circuit of said translating device and said secondelectroresponsive switch upon operation relieving said thermal device ofthe aforementioned initial thermal influence.

3. The combination with X-ray equipment, of an electrical supplycircuit, an impedance, an electroresponsive switch, a switch operable atwill to connect said X-ray equipment to said supply circuit through saidimpedance and to energize said electroresponsive switch to exclude saidimpedance from circuit for rendering said X-ray equipment active, saidswitch operable at will being biased to open position, and a thermallyresponsive switch and a second electroresponsive switch coacting todeenergize said first mentioned switch for reinclusion of saidimpedance, thereby to terminate the active period of said X-rayequipment and to maintain said equipment inactive pending release andreclosure of said switch operable at will, said thermal device beinginitially subjected to thermal influence of current of a circuitindependent of the circuit of said translating device, and said secondelectroresponsive switch upon responding freeing said thermal device ofsuch thermal influence.

4. A control device adapted to be incorporated between a supply circuitand a current consuming appliance, said device comprising in combinationa time switch having a contactor movable through a predetermined cyclefrom and to an initial position and also having a stationary contactengageable at a predetermined point in said cycle by said contactor, aline switch controlling said circuit, a relay switch having an operatingcoil connected across said circuit to closed said relay switch when saidline switch is closed, means controlled in the closing of said lineswitch for initiating the movement of said time switch contactor in saidcycle, means connected to the relay switch for energizing said appliancewhile the relay switch is closed, and means connected with the contactengaged by the time switch contactor upon its return toward said initialposition for opening said relay switch.

5. A circuit controlling device adapted to be incorporated between asupply circuit and a current consuming device, said circuit controllingdevice comprising in combination a first relay switch having a controlcoil, and a second relay switch having a control coil, a thermostatictime switch having a heating coil and a plurality of stationary contactstoward one of which said time switch is biased, the other contact beingdisposed to be engaged by said time switch at the extreme of its rangeof movement produced by said heating coil, connections from said supplycircuit to the control coil of the first relay, whereby to close saidrelay when said supply circuit is energized, connections from the supplycircuit to the heating coil, whereby to initiate the heating of saidthermostatio switch when the supply circuit is energized, connectionsfrom said supply circuit subject to the control of said first relay forthe delivery of current to the current consuming device, connectionsfrom the contact engaged by the thermostatic switch at the extreme ofits movement to the actuating coil of the second relay, said secondrelay having connections for short circuiting the heating coil of thethermostatic switch whereby to initiate the return thereof subject toits bias, and connections from the contact engaged by the thermostaticswitch upon its return for deenergizing the control coil of the firstrelay whereby to interrupt the current to the current consuming device.

6. A device for the control of current from a supply line to an X-raytube, said device comprising a manually operable switch in the supplyline, a first relay switch having a control coil, a time switch having amovable contact and stationary contacts at the extremes of the range ofmovement of the movable contact, and means for energization of the X-raytube including a series impedance connecting said last mentioned meansacross the line subject to the control of the line switch, a connectionacross the line subject to the control of the line switch for energizingthe control coil of the first relay, connections controlled by saidfirst relay shunting said series impedance whereby to subject said tubeenergizing means to full line current when said relay is closed,connections across the line subject to the control of said line switchfor energizing said time switch for movement from one of its stationarycontacts toward the other, means connected with said other time switchcontact for initiating the reverse movement of said time switch uponengagement with said other contact, and means connected with the contactengaged by the time switch upon its return to its initial position foropening said first relay whereby to restore said impedance to serieswith said tube energizing means.

7. The device of claim 6 in which the means connected with said othercontact engaged by the thermostatic switch at the extreme of itsmovement includes a second relay connected across said time switchactuating means and having a control coil self-energizing upon theclosing of said relay to hold said relay closed pending the opening ofsaid line switch.

LIONEL E. WEYENBERG.

